<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>文件上传</title>
</head>
<body>
    <h1>文件上传</h1>
    <form method="post" action="/portrait" enctype="multipart/form-data">
      用户名：<input type="text" name="username" id="aaa"/><br/>
      头像：<input type="file" name="portrait" id="bbb"/><br/>
      <button>点击提交</button>
    </form>
</body>
</html>